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Compass Issue 8
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Compass is a quarterly publication of the USDA Forest Service's Southern Research Station (SRS). As part of the Nation's largest forestry research organization -- USDA Forest Service Research and Development -- SRS serves 13 Southern States and beyond. The Station's 130 scienists work in more than 20 units located across the region at Federal laboratories, universites, and experimental forests.

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Issue 8

How Can Experimental Forests Help Us Clean Up Our Act?

Not all experimental forests are part of the Forest Service research network. Many, like the Duke Forest near Raleigh-Durham, NC, were established to offer settings for university level research and teaching. Still others were started for one purpose, but are suited for the conduct of research with changing times and shifting values.

Such is the story of the Savannah River Site (the Site), a U.S. Department of Energy facility occupying nearly 200,000 acres on the South Carolina Coastal Plain. In 1951, after purchasing its cutover forests and abandoned agricultural fields, the Federal Government closed the Site to public access to begin production of nuclear weapons materials. At about the same time, the Forest Service was selected to manage the natural resources and began a program of reforestation, accompanied by an ecological survey, conducted by universities that served as a baseline for future work.


In 1972, the Site became the first of seven national environmental research parks—places set aside to conduct ecological studies and develop tools to offset the effects of human actions on the environment. This designation encouraged scientists from SRS and other organizations to begin studies looking at science problems of regional and national interest. These include minimizing environmental impacts of forest management; understanding ecological patterns and processes that are fundamental to conservation; and ecological restoration of red-cockaded woodpeckers and other endangered species, wetlands, savannas, and upland forest communities.

New challenges, new approaches

Over the years the Site has grown into a preferred research location for several reasons: it is off-limits to casual visitors who might disturb study plots, its land management plans encourage research and provide greater flexibility for studies, and it has a resident Forest Service staff that supports the design and implementation of projects.

One famous series of studies in the 1980s was conducted under the leadership of Don Marx, a SRS research pathologist who pioneered methods designed to help trees reestablish on highly disturbed sites by restoring their symbiotic relationships with the mycorrhizal soil fungi that naturally occur on tree roots. The techniques Marx developed at the Site were adopted worldwide. In 1991, the Marcus Wallenberg Foundation presented him with its 2 million Swedish krona prize, the forestry equivalent of the Nobel. The Wallenberg Prize recognized Marx’s work in developing “selective mycorrhizal inoculation of tree nursery soils which greatly increases the growth and survival rates of conifer seedlings used in the reforestation of inhospitable soils.”

Today, many natural resource decisions are shaped by human as well as physical and biological influences. Many of the challenges that society faces require answers within a larger context and over longer time frames, forcing a shift in research approach from the experimental plot to the experimental landscape. “In ecological research, the most meaningful results come from studies that take into account the effects of the passage of time, changing biological and physical conditions, and variations across landscapes. Of these three factors, the first two—elapsing time and changing conditions—are relatively straightforward to test and replicate using small study plots.” said John Blake, research coordinator at the Site. “The third factor—variations across landscapes— is more complicated and has been traditionally addressed through modeling, applying results from the small plots along with observations of species and geographic patterns. Using entire landscapes instead of plots in experimental designs allows scientists to control changes in conditions so they can identify critical relationships—but at a scale that is appropriate to the biological or physical processes involved.”

Recently, scientists at the Site have taken the next step toward an experimental landscape approach by establishing several extremely large manipulations to test mainstream environmental and ecological concepts. Two nationally important studies in particular show the value of using large landscapes in solving today’s research questions. One examined the role of “corridors” in plant and animal population conservation; the other involved the simultaneous restoration of close to 20 Carolina bays, the small depressional wetlands once common to the area.

Elegant research with practical applications

Phytoremediation, the use of plants to remove contaminants from soils and water, is another application that has benefited from the experimental landscape approach pioneered at the Site. As phytoremediation systems are applied under increasingly stringent regulatory conditions, the scientific basis for their design and operation has become critical to their success and their acceptance by both the regulators and the public.

Building on earlier work by Wayne Swank at the SRS Coweeta Hydrologic Laboratory on the processes that control evapotranspiration (water escaping into the atmosphere from plants and soils) and by scientists on the Crossett Experimental Forest on water uptake in trees, a new generation of SRS and university scientists and Savannah River managers devised an innovative approach for capturing tritium, a nuclear isotope of hydrogen, and removing it from the ground water before it reaches surface waters. Together the scientists and managers developed a watershed scale irrigation system that moved tritium-laden water into surrounding forests on the Site with the expectation—derived from previous forest hydrology research— that the trees would draw up the tritium along with the water. The project had many unknowns. Among them were questions about the amount of material that could be applied throughout the year; the influence of various kinds of vegetation, soils, and roots on the treatment process; and the necessary thresholds for avoiding waterlogging and minimizing movement of contaminated water below the root zone.

The phytoremediation system they developed enabled the Site to meet streamwater-quality objectives using living trees, rather than other, more expensive alternatives. As a bonus for the scientists, the tritium in the water served as a tracer in soils and trees, providing a unique opportunity to test fundamental assumptions about evapotranspiration processes and water uptake in a real forest watershed. Mark Coleman, a SRS research biologist, is continuing to support this effort with biomass research that will allow for the expansion of treatments to more productive and easily managed pine plantations.

The partnerships formed at the Site have created a rich environment for productive research by SRS and many universities. To further those partnerships, the Forest Service and the nearby County of Aiken have established a new research laboratory outside the gates of the Site that combines facilities for research and development with those for incubating new businesses. “We are very excited about the potential of this new facility to further the research mission and to give back to the community that has supported us so well in the past,” said Blake. —CW

Savannah River Site:

For more information: John Blake at 803–725–8721or

Research on short-rotation woody crops at the Savannah River Site contributes to both phytoremediation and bioenergy research.
Research on short-rotation woody crops at the Savannah River Site contributes to both phytoremediation and bioenergy research. (Forest Service photo)